The group defined compact housing as construction that's twice as dense as current development, and assumed it would occur at the urban fringe and through some infill in cities (as opposed to focusing on making existing housing more dense).

So what are the benefits to the climate?

According to this study, they were fairly modest. Assuming:

75 percent of development is compact...

leads to residents driving 25 percent less...

the result is vehicle miles traveled, fuel use, and CO2 emissions of new and existing households would decline up to 8 percent by 2030, increasing to up to 11 percent by 2050.

But if you add to the increase in density some improvements in public transit and alternative transportation, vehicle miles traveled can drop 25 percent, which starts to make a real difference.

The report is a blueprint for changing policy and tax structure to encourage more dense development. Its focus is California, but the recommendations could be applied anywhere.

First it identifies four roadblocks to increasing density (which it also calls "sustainable development," "compact," "transit oriented," "smart growth," "infill," and my fav, "new urbanist." So chic!). The challenges, which I'm quoting directly:

Inadequate infrastructure: a lack of public transit, insufficient, or aging utilities, and under-performing schools in city centers and other areas that are prime locations for sustainable development.

Higher economic costs: a typically more expensive construction process, longer permitting time, and additional infrastructure burdens make sustainable development in existing neighborhoods less economically competitive than constructing in undeveloped areas.

Their bottom-line is that the regulations and incentives to get smart growth take place at the local level, but require action from the state and federal government to take hold. If you're really interested, it's worth reading all of the report's recommendations (the whole thing is only 23 pages), but some that struck me:

At the local level, change building fees and permits for sustainable projects to reduce or eliminate those costs. Create policy to support and facilitate infill near transit hubs.

For state governments, shift discretionary funds away from new highway projects towards infrastructure investments in high-density areas. Eliminate sales and property taxes that lead local governments to prefer big commercial developments over mixed use.

At the federal level, spend federal money (grants, contracts, etc.) on sustainable projects. Make it easier for projects to get federal-loan guarantees by removing the Federal National Mortgage Association requirement that condos are 70 percent pre-sold.

The report also has recommendations for supporting and increasing the reach of industry leaders in sustainable development.

There's plenty of reason for Puget Sound area leaders to take a look at both studies. As Doug MacDonald points out in this recent piece in Crosscut, the area is failing to meet its density goals according to new population data. MacDonald, the former head of the Washington state Department of Transportation, in particular highlights the need to pay attention to Transportation 2040. The plan is being drafted by the Puget Sound Regional Council and will help shape transportation decisions for the next 30 years.